Safety switch for well pumping units



A ril 21, 1942; c. R. ATHY 2,280,114

SAFETY SWITCH FOR WELL PUMPING UNITS Filed Jan. 19, 1939 CZif'f'ord P1272? Patented Apr. 21, 1942 SAFETY SWITCH FOR WELL PUMPING UNITS Clifford R. Athy, Columbus, Ohio, assignor to International-Stacey Corporation, Columbus, Ohio, a corporation of Ohio Application January 19, 1939, Serial No. 251,732

7 Claims.

7 This. invention relates generally to well pumping mechanism and more particularly to a safety switch mechanism. provided for the purpose of protecting the equipment in the event of failure of one or more of the. parts. Frequently, in the pumping of wells, parts of the equipment fail and if the application of the driving force is not immediately discontinued, additional parts of the mechanism are seriously jeopardized.

The primary object of this invention is .the provision of a safety device which will cut oil the driving force practically simultaneously with the failure of any of the important parts such as. the rods, cables, pitmans or belts or the displacement of a counterweight.

Another object resides in the provision of a safety switch which will be operated by sudden jars or jolts applied to the walking beam of the well operating mechanism.

Still another object resides inthe provision of a gravity operated switch having magnetic means for resisting the movement of the switch operating mechanism in response to the force of gravity and, in addition, the. provision of means for varying the sensitivity of the magnetic means.

A further object. rests in the provisions of a I switch of the character mentioned having a minimum number of moving parts andone which will give continuous service over long periods of time without special attention.

Other objects will be apparent from the following description and the accompanying drawing in which the invention has been illustrated. In the drawing:

Fig. 1 is aside elevational View of. a well pumping mechanism provided with the safety switch forming the subject matter of the present invention;

Fig. 2 is. a. vertical longitudinal sectional view taken through the safety switch mechanism;

Fig. 3 is a vertical transverse sectional view mechanism includes a base I from one end of which arises a Samson post 2. The opposite end of the base is provided with an electric motor 3 which serves as the driving force of the equipment. Adjacent to the motor, the base carries a gear reduction transmission 4 to which power is conveyed from the motor by means of V-belts 5. The transmission includes a shaft 6 carrying a crank I and extending upwardly from the crank is a pitman 8 connected at its upper end to a walking beam 9 which is pivoted for rocking movement on the upper end of the Samson post. The end of the walking beam opposite that to which the pitman is connected is provided with a mule head 10 having a cable I l secured thereto. The lower end of the cable supports a polished rod grip 12 in vertical registration with a well bore. The polished rod extends from the grip into the well where it connects to the sucker rods from which the. piston of the well pump is suspended.

The foregoing mechanism is of the general type used in operating wells and forms no part of the present invention. In the operation of such a mechanism, the rods or the pitmans frequently fail and if the driving force is not immediately discontinued, the remaining mechanism is subjected to severe strains which may cause it to be broken or otherwise rendered unfit for further use. To prevent this, a safety switch mechanism I3 is secured to the beam. The switch mechanism is operated upon the failure of any of the parts to stop the motor. The switch mechanism includes a body 14 formed from a metallic casting and having an. internal chamber IS in which the switch mechanism is positioned. The rear of the body has a plate l6- secured thereto, to the rear surface of which is welded a U-shaped member ll. One flange of this member is formed with a threaded opening for the reception of a set screw I8 employed in clamping the plate I6 and the body M to one flange of the walking beam or other suitable support.

In the chamber l5 there is pivotally secured to the rear wall of the body a lever l9 which has a screw 2.0 extending through an opening in one end to form the pivot about which the lever may move. The opposite end of the lever is disposed exteriorly of the body and is provided with a balance weight 2|, the purpose of which will hereinafter be set forth. Adjacent to the pivotal point of the lever, the rear wall of the body is formedwith a boss 22 from which a bolt 23 projects into the chamber IS. A horeshoe-shaped permanent magnet 24 is securely clamped against the boss by means of nuts 25 carried by the bolt 23. The magnet is positioned above the lever l9, and, in registration with the magnet, the lever carries a block 25 formed from a material highly responsive to magnetic forces. When the lever is moved on its pivot in opposition to the force of gravity to its uppermost position, the block will be engaged with the magnet and the lever will then be yieldably held against downward movement. If a sudden upward movement is imparted to the beam, the weight of the lever l9 and the balance member 2| is sufficient to overcome the force exercised by the magnet upon the block 26 and. the lever will move away from the magnet to its lowermost position. By adjusting the balance member longitudinally of the lever, the effective weight may be changed and the responsiveness of the lever to the sudden upward movement of the beam varied. The lever 19 at a point within the body has a plate 21 rigidly secured thereto. This plate carries at its lower portion a clip 28 to hold a mercoid switch 29.

In the form of the invention shown, the switch is tilted to such a position that the mercury will be disposed in engagement with the contacts. The switch 29, as shown in Fig. 4, is connected in a circuit including a relay switch 30 employed to control the flow of current to the motor 3. As long as the lever I9 is held in its uppermost position by the magnet 24, the circuit to the relay switch will be completed. At the time a sudden jar is transmitted to the walking beam, the lever will move away from the magnet and the mercury in the switch will flow out of engagement with the contacts to interrupt the flow of current to the relay switch. The deenergizing of the coil of the relay will result in permitting the armature of the relay switch to move to such a position as will discontinue the flow of current to the motor 3 and the flow of power to the well operating mechanism will be stopped. The mechanism may be returned to an operative state merely by returning the lever l9 to its elevated position whereby the block 26 will be engaged with the magnet 24.

In the preferred form of the invention, the lever is formed from a material not affected by the magnetic forces. It is obvious, however, that the block 26 may be eliminated if the lever is formed from steel or other material responsive to the forces of the magnet.

In the modified form of the invention shown in Fig. 5, an electromagnet has been substituted for the permanent magnet. The operation of this device will, however, be identical with that shown in the preferred form. The lower end of the body M has a supplemental compartment 3| in which are positioned terminals 32 to which the conduits leading from the switch are connected. The wires extending to the relay switch and current supply are connected to the ends of the terminals disposed in the chamber 3!. The bottom of the casing is provided with an opening through which access may be had to the terminals when it is desired to connect or disconnect the wires thereto. This opening is covered by a removable plate 33 as is also the open front of the main body of the casing.

In Fig. 6, the safety switch has been illustrated in combination with the ignition circuit of an internal combustion engine. When employed with this type of prime mover. the switch 29a is disposed in such a position as to space the mercury from the contacts, one of which is grounded, and the other connected in the ignition circuit between the coil 34 and the magneto 35. When the lever [9 has moved away from the magnet 24 a distance sufiicient to permit the mercury in the switch to connect the contacts, the coil will be' short circuited and the engine will stop. The switch mechanism in this form is identical with that described in the preferred form with the exception of the position of the mercury tube.

While I have shown and described the invention in its preferred form, numerous minor changes may be made therein without departing from the fundamental principle of operation and it is my desire to reserve the rights to all such changes as may be said to fall within the scope of the appended claims.

I claim:

1. A circuit controlling device comprising a body, a lever pivotally connected at one end to said body, a permanent magnet secured to said body above said lever, a magnetism responsive member carried by said lever in registration with said magnet, the magnetic force exerted upon said member being sufficient under normal conditions to resist movement of said lever in response to gravitational force, switch means carried by said lever and operated by movement thereof in response to gravitational force to control current flow through a circuit in which the switch is disposed, and a balance weight positioned for longitudinal adjustment on said lever to vary the effectiveness of said magnet.

2. A circuit controlling device comprising a body, a lever pivotally connected to said body, a permanent magnet secured to said body in registration with said lever, a magnetism responsive member carried by said lever in registration with said magnet, the magnetic force exerted upon said member being sufiicient under normal conditions to resist movement of said lever in response to gravitational force, switch means carried by said lever and operated by movement thereof in response to gravitational force to control current flow through a circuit in which the switch is disposed, and a balance weight positioned for longitudinal adjustment on said lever to vary the effectiveness of said magnet.

3. A circuit controlling device comprising a body, a lever pivoted at one end on said body for pivotal movement in a vertical plane, a mercury switch carried by said lever, a magnet positioned on said body in registration with said lever and normally operating to hold said lever in a substantially horizontal position to maintain said switch in circuit closing position, and weight means carried by said lever adjacent the free end thereof, said weight being adjustable to vary the force required to hold said lever in a switch closing position.

4. A circuit controlling device comprising a body, a lever pivoted adjacent one end on said body for pivotal movement in a vertical plane, a mercury switch carried by said lever, and a magnet secured to said body in registration with the intermediate portion of said lever and operative to hold said lever in a substantially horizontal position to maintain said switch in circuit closing position, the release of said lever from the action of said magnet serving to cause move ment of said lever in response to gravitational force to a position wherein said switch is in circuit interrupting condition.

5. A circuit controlling device comprising a body, a lever pivotally secured at one end to said body for movement in a substantially vertical plane, a weight mounted for longitudinal movement on said lever adjacent the free end thereof, mercury switch means carried by said lever and operated by movement thereof to open and close a circuit, and a magnet carried by said body and engaging said lever between said weight and the pivotal axis and operating to yieldably hold said lever in a substantially horizontal position, release of said lever from the attractive force of said magnet serving to permit movement thereof in response to gravity.

6. In well operating mechanism of the type having a reciprocating walking beam and motor driven means for moving said beam, said motor having an electric circuit connected therewith; means for automatically controlling the flow of electric current through said circuit comprising a body formed for attachment to said beam, a lever pivotally connected at one end to said body, a switch in said control circuit, said switch bein operated by movement of said lever in response to gravitational force to control the flow of current through said circuit, magnetic means yieldably resisting movement of said lever, and means for varying the efiectiveness of said magnetic means including a weight adjustably secured to said lever.

7. In well operating mechanism of the type having a reciprocating walking beam and motor driven means for moving said beam, said motor having an electric circuit connected therewith; means for automatically controlling the flow of electric current through said circuit comprising a pivoted lever carried by said beam, a switch carried by said lever and connected in said control circuit, said switch operating to control the flow of current through said circuit upon movement of said lever in response to gravitational force, and magnetic means yieldably resisting movement of said lever.

CLIFFORD R. ATHY. 

